The system must not accept ICMPv4 secure redirect packets by default.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-38532	RHEL-06-000090	SV-50333r3_rule		Medium

Description
Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2020-05-19

Details

Check Text ( C-46089r3_chk )
The status of the "net.ipv4.conf.default.secure_redirects" kernel parameter can be queried by running the following command: $ sysctl net.ipv4.conf.default.secure_redirects net.ipv4.conf.default.secure_redirects = 0 $ grep net.ipv4.conf.default.secure_redirects /etc/sysctl.conf /etc/sysctl.d/* net.ipv4.conf.default.secure_redirects = 0 If "net.ipv4.conf.default.secure_redirect" is not configured in the /etc/sysctl.conf file or in the /etc/sysctl.d/ directory, is commented out or does not have a value of "0", this is a finding.

Check Text ( C-46089r3_chk )

The status of the "net.ipv4.conf.default.secure_redirects" kernel parameter can be queried by running the following command:

$ sysctl net.ipv4.conf.default.secure_redirects
net.ipv4.conf.default.secure_redirects = 0

$ grep net.ipv4.conf.default.secure_redirects /etc/sysctl.conf /etc/sysctl.d/*
net.ipv4.conf.default.secure_redirects = 0

If "net.ipv4.conf.default.secure_redirect" is not configured in the /etc/sysctl.conf file or in the /etc/sysctl.d/ directory, is commented out or does not have a value of "0", this is a finding.

Fix Text (F-43479r2_fix)
To set the runtime status of the "net.ipv4.conf.default.secure_redirects" kernel parameter, run the following command: # sysctl -w net.ipv4.conf.default.secure_redirects=0 Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a config file in the /etc/sysctl.d/ directory (or modify the line to have the required value): net.ipv4.conf.default.secure_redirects = 0 Issue the following command to make the changes take effect: # sysctl --system

Fix Text (F-43479r2_fix)

To set the runtime status of the "net.ipv4.conf.default.secure_redirects" kernel parameter, run the following command:

# sysctl -w net.ipv4.conf.default.secure_redirects=0

Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" or a config file in the /etc/sysctl.d/ directory (or modify the line to have the required value):

net.ipv4.conf.default.secure_redirects = 0

Issue the following command to make the changes take effect:

# sysctl --system